玻璃化转变
结晶
结晶学
材料科学
多态性(计算机科学)
晶体生长
扩散
Crystal(编程语言)
分子动力学
放松(心理学)
化学物理
热力学
化学
聚合物
计算化学
程序设计语言
基因型
复合材料
物理
基因
社会心理学
生物化学
计算机科学
心理学
作者
Ye Sun,Hanmi Xi,Shuang Chen,M. D. Ediger,Lian Yu
摘要
A remarkable property of certain glass-forming liquids is that a fast mode of crystal growth is activated near the glass transition temperature Tg and continues in the glassy state. This growth mode, termed GC (glass-crystal), is so fast that it is not limited by molecular diffusion in the bulk liquid. We have studied the GC mode by growing seven polymorphs from the liquid of ROY, currently the top system for the number of coexisting polymorphs of known structures. Some polymorphs did not show GC growth, while others did, with the latter having higher density and more isotropic molecular packing. The polymorphs not showing GC growth grew as compact spherulites at all temperatures; their growth rates near Tg decreased smoothly with falling temperature. The polymorphs showing GC growth changed growth morphologies with temperature, from faceted single crystals near the melting points, to fiber-like crystals near Tg, and to compact spherulites in the GC mode; in the GC mode, they grew at rates 3−4 orders of magnitude faster with activation energies 2-fold smaller than the polymorphs not showing GC growth. The GC mode had rates and activation energies similar to those of a polymorphic transformation observed near Tg. The GC mode was disrupted by the onset of the liquid's structural relaxation but could persist well above Tg (up to 1.15 Tg) in the form of fast-growing fibers. We consider various explanations for the GC mode and suggest that it is solid-state transformation enabled by local molecular motions native to the glassy state and disrupted by the liquid's structural relaxation (the α process).
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